LHC physics debris collimation studies and their impact on AFP detectors acceptance

The ATLAS Forward Proton (AFP) group is proposing to upgrade the forward region of ATLAS by installing forward proton detectors at 220 m and 420 m from the interaction point on both sides of the LHC ATLAS experiment. For this purpose, at both the 420 m and 220 m locations, it is proposed to install movable beam pipes which will host silicon tracking and fast timing detectors (i.e. four independent detector stations). The experimental acceptance at 220 m is dependent upon the setting of two collimators designed to protect the LHC straight section and dispersion suppressor around ATLAS (and CMS) from the physics debris generated at the two high luminosity experiments. This note presents the result of tracking studies showing that the installation of a new collimator in front of the Q6 magnet (or the displacement at this of location of the second of the already existing collimators) would ensure an improved protection of the LHC machine while allowing the AFP experiment at 220m.